Quality control methods for

N,N,N',N'-Tetramethyl-p-phenylenediamine dihydrochloride R. C
10
H
16
N
2
, 
2HCl.
Description. Whitish grey crystals. 
A suitable commercially available reagent. 
 
Thionine R. C.I. 52000; C
12
H
10
ClN
3
S.
Description. Blackish green glistening crystals.
Solubility. Freely soluble in hot water. 
A suitable commercially available reagent. 

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Quality control methods for medicinal plant materials 
Thionine TS. 
Procedure. Dissolve 0.2 g of thionine R in 100 ml of ethanol (∼188 g/l) TS. 
 
Toluene R. C
7
H
8
. 
A suitable commercially available reagent. 
2,2,4-Trimethylpentane R. C
8
H
18
. 
A suitable commercially available reagent. 
Trinitrophenol R. C
6
H
3
N
3
O
7
. 
A suitable commercially available reagent. 
 
Trinitrophenol, ethanolic, TS. 
Procedure. Dissolve 1 g of trinitrophenol R in 100ml of ethanol (∼750g/l) TS. 
Tropaeolin O R. C.I. 14270; E103: resorcin yellow; chrysoin S; sulpho orange; 
acid orange 6; C
12
H
9
N
2
NaO
5
S. 
Description. Produces a yellow colour in moderately alkaline solutions and an 
orange colour in strongly alkaline solutions (pH range 11.0-12.7). 
A suitable commercially available reagent. 
 
Water, carbon-dioxide-free, R. Water that has been boiled vigorously for a few 
minutes and protected from the atmosphere during cooling and storage. 
 
Xylene R. C
8
H
10
. 
A suitable commercially available reagent.